multivariate_testing.js

(function () {
// Variables
  var testID = '001';
  var testDays = 8;
  var randomNumber = {{Random Number}};
  var testVariant = readCookie(testID);
  var previewUrl = true;
  var prefix = 'tnw-';
  var changes;
  changes = {
    1: {
      variants: {
        1: {
          execute: function () {
            //
          }
        },
        2: {
          execute: function () {
            //
          }
        }
      }
    },
    2: {
      variants: {
        1: {
          execute: function () {
            //
          }
        },
        2: {
          execute: function () {
            //
          }
        }
      }
    }
  };

// Helpers
  function setCookie(testID, changeID, variantID, testDays) {
    if (typeof(testDays) === 'undefined') testDays = 8;
    var date = new Date();
    date.setTime(date.getTime() + (testDays * 86400000));
    var expires = '; expires=' + date.toGMTString();
    document.cookie = prefix + testID + '=' + changeID + '-' + variantID + expires + '; path=/';
  }

  function readCookie(testID) {
    var nameEQ = prefix + testID + '=',
        ca = document.cookie.split(';');

    for (var i = 0; i < ca.length; i++) {
      var c = ca[i];
      while (c.charAt(0) == ' ') c = c.substring(1, c.length);
      if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length, c.length).split('-');
    }
    return null;
  }

  function checkCookie(name) {
    ca = document.cookie.split(';');
    for (var i = 0; i < ca.length; i++) {
      var c = ca[i];
      while (c.charAt(0) == ' ') c = c.substring(1, c.length);
      if (c.indexOf(name) > -1) return true;
    }
    return false;
  }

  function sendDimension(change, variant) {
    if (checkCookie('_ga')) ga("set", 'dimension10', prefix + testID + '-' + change + '-' + variant);
  }

  function getParameterByName(name) {
    name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
    var regexS = "[\\?&]" + name + "=([^&#]*)";
    var regex = new RegExp(regexS);
    var results = regex.exec(window.location.search);
    if (results == null) {
      return "";
    } else {
      return decodeURIComponent(results[1].replace(/\+/g, " "));
    }
  }

  function control(testChange, testVariant) {
    setCookie(testID, testChange, testVariant, testDays);
    sendDimension(testChange, testVariant);
  }

  function variant(changeID, variantID) {
    control(changeID, variantID);
    if (changeID > 0) changes[changeID]["variants"][variantID].execute();
    if (variantID > 0) changes[changeID]["variants"][variantID].execute();
  }

// Check variants v.s. cookies
  if (previewUrl && getParameterByName('previewUrl') != "") {
    variant(getParameterByName('previewUrl'));
  } else if (testVariant) {
    variant(testVariant[0], testVariant[1]);
  } else if (!checkCookie(prefix)) {
    var chosen = 0,
        random1 = Math.round((Math.random() * Object.keys(changes).length));
    for (var j = 0; j <= Object.keys(changes).length; j++) {
      if (random1 == j) {
        var random2 = Math.round((Math.random() * Object.keys(changes[j]["variants"]).length));
        variant(j, random2)
      }
      chosen++;
    }
  }
}());